Hwy panic stop -- rears locked up

[mattbta]

Had a panic stop moment yesterday on the highway and when I stabbed the brakes the rear tires locked up and gave quite the squeal. I am confused because it didn't seem like the ABS kicked in at all....the pedal didn't give the usual feedback that I'm used to on ABS.

I have two years on Wagner pads/rotors all the way around and Timken front hubs. No lights on the dash, SES or ABS.

Any ideas? Braking outside of that is great. I'm sure my cheapo BT OBDII can't show brake system info.

 

[Doubeleive]

Had a panic stop moment yesterday on the highway and when I stabbed the brakes the rear tires locked up and gave quite the squeal. I am confused because it didn't seem like the ABS kicked in at all....the pedal didn't give the usual feedback that I'm used to on ABS.

I have two years on Wagner pads/rotors all the way around and Timken front hubs. No lights on the dash, SES or ABS.

Any ideas? Braking outside of that is great. I'm sure my cheapo BT OBDII can't show brake system info.

ABS could have errored out and not have thrown a code if it self checked and passed, it's not a perfect system brakes will always default to regular braking if the system doesn't operate for any reason. the good news is you can stop if you need to.

 

[OR VietVet]

Even though I agree 100% with Wes, I would still open up the rear brakes and have a look see. Perhaps something is amiss back there that allowed this lock up to happen and not allow the ABS system to work as you expected.

 

[mattbta]

Are there any ABS sensors on the rear wheels?

 

[OR VietVet]

It always helps to be given the year, make and model when you post with questions. Maybe put it in your signature. Typically the rear speed sensor is on the trans. Is your rig 4wd or Rwd?

 

[rockola1971]

GO lock it up in a parking lot and see if the ABS works.

 

[Wylie_Tahoe]

I think these chassis are a 3-sensor system, using the speedo pickup as the rear ABS. Each front wheel has its own sensor.

 

[mattbta]

2004 RWD JL4. Looks like I have two rear sensors based on what I'm seeing. ( 15063810 )

Will get out to a parking lot and try and also climb underneath and look around.

 

[OR VietVet]

Yes, it does look like that.

https://www.rockauto.com/en/moreinfo.php?pk=1416248&cc=1424247&jsn=948

 

[Doubeleive]

the rear sensors are on the axle housing behind the wheel bearing, unless you have a abs light on then the sensors are working, I have made a abs system lock up the wheels before, I have also been a lunatic behind the wheel